The present invention refers to an outlet device for a jet engine, including an outlet channel, which defines a main flow direction for a jet from the jet engine, wherein the outlet channel has an upstream end for being connected to the jet engine and a downstream end, wherein the outlet channel in the proximity of the downstream end has an elongated shape, seen in the flow direction, and includes at least two outlet portions, which are separated from each other, for a respective outlet flow of said jet. The invention also refers to an aircraft including a jet engine.
Typical aeroplanes, which are driven by one or several jet engines, beside the forward wings today frequently have a tail portion with a fin and two stabilising wings. On the fin a side rudder is normally provided for the steering of the aeroplane in a lateral direction. On the stabilising wings, or in certain cases on the main wings for instance on so called delta wings, elevators are provided for the steering of the aeroplane in a vertical direction. Such a tail portion involves a complicated design work for obtaining the desired aerodynamic properties and manoeuvring possibilities of the aeroplane. It is in certain cases desired to have a tail portion which has a more simple design. Furthermore, the manoeuvring possibilities which may be obtained by such conventional rudders may be experienced to be insufficient, in particular if the aeroplane is propelled at a low speed.
By jet engine it is, in the present application, referred to all available jet engines, such as turbo jet engines, double jet engines, turbo fan engines, ram-jet engines, pulse-jet engines, rocket engines etc.
U.S. Pat. No. 3,570,247 discloses an outlet nozzle for a jet engine. The outlet nozzle includes two outlet portions, which are provided beside each other. Each outlet portion includes guide flaps for controlling the flow in a vertical plane.
The object of the present invention is to provide an alternative design of an outlet device of an aircraft with a jet engine. In particular, it is aimed at an outlet device which permits appropriate manoeuvring possibilities of the aircraft and a more simple design of the tail portion of the aircraft.
This object is obtained by the outlet device initially defined, which is characterised in that at least a first of said outlet portions includes means for controlling the outlet direction of the outlet flow in a first plane and that at least a second of said outlet portions includes means for controlling the outlet direction of the outlet flow in a second plane, which forms an angle to the first plane.
By designing the outlet with two separate outlet portions, it is possible to obtain a jet which has a stabilising effect on the flying of an aircraft. Depending on the direction of the outlet flows from both the outlet portions a certain tipping moment and rolling moment may be obtained. By such an outlet device, it is thus possible to replace the corresponding dynamic rudders of a conventional aeroplane and in such a way obtain a simplified aeroplane design. It is possible, by means of the outlet flows, to provide determined moving moments of an aeroplane, for instance yaw moment, tipping moment or rolling moment. Thereby, said control means of said outlet portions may function as the elevator of the aeroplane and thus steering the aeroplane in a vertical direction, and as the side rudder of the aeroplane and thus steering the aeroplane in a horizontal direction. By directing one of the outlet flows obliquely upwardly and the other outlet flow obliquely downwardly, a rolling moment may be obtained, for instance. Except for the fact that such an outlet device gives the tail portion of the aeroplane a simplified design, a very good authority of the steering is obtained by such a control, i e the aeroplane will respond very well to changes in the direction of the outlet flows. Furthermore, such a control in a vertical direction is very useful when an aeroplane is propelled at relatively low speeds.
According to a further advantageous embodiment of the invention, said control means of said first outlet portion are arranged to control the outlet flow concerned independent of said control means of said second outlet portion. In such a way it is possible to direct the flow from each of the outlet portions in a respective desired direction for providing a substantially arbitrary moving moment of the aeroplane.
According to a further embodiment of the invention, said outlet portions are provided beside each other seen in said section. Thereby, a wall portion may be provided between two adjacent ones of said outlet portions in order to separate the different outlet flows from each other.
According to a further advantageous embodiment of the invention, said outlet portions include a central outlet portion and two lateral outlet portions, one at each side of the central outlet portion. Thereby, said control means of the lateral outlet portions may advantageously be arranged to control the outlet flow concerned in the first plane, and said control means of the central outlet portion may be arranged to control the outlet flow concerned in the second plane. In such a way one may steer an aeroplane in a vertical direction by means of the lateral outlet portion, and in a lateral direction by means of the central outlet portion. In such a way, both the stabilising wings with the elevators and the fin with the rudder on a conventional aeroplane may be replaced by the outlet device according to the invention.
According to a further embodiment of the invention, a said control means includes at least one guide flap of each outlet portion. Said guide flap is preferably rotatable about an axis, which extends substantially across the flow direction. Advantageously, said control means may include at least two guide flaps of each outlet portion, wherein the rotary axis of one of the guide flaps extends substantially in parallel with the rotary axis of the other guide flap. The two guide flaps may be provided at a distance from each other and arranged to enclose the outlet flow concerned between each other. In such a way one may in an efficient manner control the outlet flow in a desired direction which may form an angle with the flow direction. Said outlet portion may also include at least a third guide flap, which is provided between the two guide flaps and which is rotatable about a rotary axis, which extends substantially in parallel with the rotary axis of the two guide flaps.
The object is also obtained by an aircraft, which includes a jet engine and an outlet device as described above. Thereby, the outlet device may advantageously be provided at a tail portion of the aircraft. It is also possible to provide the outlet device downstream of a jet engine, which is mounted beneath a wing of the aircraft. The aircraft may form an aeroplane, a rocket or a missile.